The present invention relates to toilet flushing apparatus of the type capable of selectively dispensing either of two different volumes of water from a water closet.
The desirability of conserving water in the household is ever-increasing for water, in most parts of the world, is becoming less plentiful and, hence, more expensive. The single largest water-consumption device in the household is, of course, the toilet. Typically, with every flick of the finger, between three and seven gallons of water is consumed when, on the majority of occasions, only about half that amount need be used to fully refresh and replenish the toilet bowl. Being such a notorious water guzzler, is there any wonder that literally hundreds of inventors have focused attention over the years on devising apparatus by which either a full flush or a reduced flush can be readily achieved? Certainly the patent literature is repleat with so-called "dual flush" devices which reflect their noble efforts. Notwithstanding the apparent need, no dual flush device devised to date has received widespread commercial acceptance.
In U.S. Pat. No. 3,945,056, for example, there is disclosed a "modification kit" by which a conventional toilet of the flush tank type may be converted to a dual flush system. This conversion kit is advantageous from the standpoint that it makes use of most of the components of a conventional flushing system, including the flushing handle mounted on the outside of the water closet (flush tank). For a partial flushing, the operator merely depresses and releases the flush handle in the normal manner. When this is done, a flapper valve is removed from a valve seat to a position in which it floats above the valve seat. After a predetermined volume of water passes through the valve seat and enters the toilet bowl, a rather complex mechanism engages the flapper valve and positively urges it toward its sealing position in which it prevents further escape of water from the tank. For a full flush, the user is required to depress the flush handle and, rather than release it, he must pull it upwardly, thereby disabling, by a comparably complex second mechanism, the mechanism which would otherwise produce a partial flush. Aside from the complexity of the system per se, the requirement for the user to operate the flush lever in a non-conventional (push down/pull up) manner is disadvantageous.
While other inventors have devised dual flush mechanisms which are mechanically simpler than that mentioned above, such systems cannot be readily adapted to make use of the existing hardware of conventional water closets, and none has proven so reliable and low-cost as to be commercially viable.